For next high-speed Ethernet (Ethernet is a trademark; the same will apply hereinafter) after currently prevailing 10 Gigabit Ethernet (10 GbE), 40 Gigabit Ethernet (40 GbE) and 100 Gigabit Ethernet (100 GbE) were standardized in 2010 by IEEE 802.3ba Task Force (see NPL 1). Although 10 GbE provides for the 10 GBASE-LX4 specification based on Coarse Wavelength Division Multiplex (CWDM), the main body thereof is 10 GBASE-SR/LR/ER based on serial transmission.
On the other hand, in 40 GbE and 100 GbE, although the 40-Gb/s serial transmission standard is provided, its main scheme is parallel (multi-lane) transmission with 4 channels (40 GBASE-SR4/LR4: 10 Gb/s×4=40 Gbps, 100 GBASE LR4/ER4: 25 Gb/s×4=100 Gb/s) or 10 channels (100 GBASE-SR10: 10 Gb/s×10=100 Gb/s), taking into account transmission distance, device operation speed, cost, and the like.
Moreover, for a power saving technology in Ethernet, IEEE 802.3az Energy Efficient Ethernet (EEE) was standardized in 2010 (NPL 2). This standard is comprised of two technologies, namely: the LPI (Low Power Idle) scheme, in which when there is no data for transfer, the state is fallen in sleep, during which a heart beat signal (also referred to as a refresh signal) is transmitted to distinguish it from a link fault and allow its aliveness to be checked; and Rapid PHY Control, in which transmission rate is slowed. However, in IEEE 802.3ba Ethernet Task Force, no discussion has been given on power saving through the adaptive control of Ethernet interface depending on traffic.
PTL 1 discloses a technology in which the traffic volume in a low-speed Ethernet is monitored, and an increase or a decreased in the number of lanes used at 40 BbE or 100 GbE interface is determined depending on the traffic volume. In the case where the number of lanes is decreased, a lane or lanes used at 40 GbE or 100 GbE interface are suspended, and thereafter a lane or lanes used at 40 GbE or 100 GbE interface of the device at the other end are suspended. In the case where the number of lanes is increased, a lane or lanes unused at 40 GbE or 100 GbE interface are restored, and thereafter a lane or lanes unused at 40 GbE or 100 GbE interface of the device at the other end are restored.